PHILADELPHIA (973espn.com) - In the modern-day NFL where there are strict limitations on the time you can spend with your players the offseason has become the time for teaching before the evaluation really kicks in during training camp.

That means the "voluntary" aspect of the football calendar is far more important for younger players trying to gain a foothold in any organization.

With that in mind here are the Eagles players who need to stand out once the team's on-field OTAs begin at the NovaCare Complex on Tuesday:

- WR Mack Hollins - Hollins isn't fighting for a roster spot but the Eagles understood they needed an upgrade from Torrey Smith outside the numbers opposite of Alshon Jeffery.

Instead of staying in-house and earmarking Hollins for the spot, Howie Roseman dipped into free agency to sign the speedy Mike Wallace, a clear indication that Philadelphia doesn't believe Hollins is ready for a significant role on the team's dynamic offense just yet. The second-year player can begin changing that narrative because he will get added reps with Jeffery spending his spring rehabbing from shoulder surgery.

- DT Elijah Qualls - A big body on the defensive interior, Qualls wasn't in the best shape as a rookie and needs to show he has learned to be a professional in Year 2 of his career.

The result of that could mean anything from a big role in Jim Schwartz's defensive line rotation if Qualls is ready or a trip to the waiver wire if he's not. With Tim Jernigan out for four to six months after recent back surgery and veteran free-agent pickup Haloti Ngata rehabbing from a torn biceps that ended his 2017 season in Detroit, Qualls and third-year man Destiny Vaeao should get plenty of looks with the first-team defense.

- TE Billy Brown - With the Eagles adding second-round pick Dallas Goedert and free agent Richard Rodgers at the position, Brown needs to really flash in the spring if he wants to make a run at a roster spot come August.

A king-sized receiver in college at Shepherd, Brown hopes to prove he can be consistent catching the football and also help in-line as a blocker. Because there is no contact in the spring Brown will not be able to show if his 255-pound body can handle the latter but he can show that he understands the position in this offense.

- RB Donnel Pumphrey - Pumphrey simply wasn't strong enough as a rookie fourth-round pick and he has to prove that he is an NFL player from a physical standpoint. He's obviously always going to be undersized but there's a difference between that and not having the baseline in the weight room to be a situational back.

Pumphrey managed only five reps on the 225-pound bench press at the scouting combine back in 2017 and that showed up in August of last year when the pads went on. He is on the clock now after a redshirt season and his progress in the weight room will be monitored.

- S Tre Sullivan - Corey Graham played 60 percent of the Eagles' defensive snaps last season. The veteran's experience and football IQ gave Schwartz the confidence to use the versatile Malcolm Jenkins all over the field.

Graham remains on the open market and Philadelphia could still bring him back but he will turn 33 in July so the team would like to get younger and cheaper at the position if at all possible. Sullivan, a former college teammate of Brown at Shepherd who spent part of last season on the practice squad, is in the mix but needs to gain Schwartz's confidence when it comes to assignment football.

- CB Sidney Jones - There will be moving parts at the cornerback position in order to replace Patrick Robinson in the slot and Plan A involves Jones being ready to hit the ground running. A first-round talent who missed all but the meaningless Week 17 in his rookie season after tearing his Achilles at Washington's pro day, Jones needs to show he's ready to play 60 to 70 percent of the defensive snaps at a high level.

-John McMullen covers the Eagles and the NFL for 973espn.com. You can reach him at jmcmullen44@gmail.com or on Twitter @JFMcMullen

Want more NFL? Check out John's piece on why the comparison between Jared Goff and Mitchell Trubisky needs a little more nuance at GetMoreSports.com.